if you want to use ubuntu + postfix + laravel to do a mass email system. 
 but if there are too many emails, it will be 504 if you send them for a while. This problem can be solved with set_time_limit (0) 
 but feels too inefficient. 
 is there any other way to directly give the recipient address to postfix at once? 
 ask postfix to send more than one email at a time? 
 ask experienced friends to coach 
